Contribution Of The E2 Transitions To The Opacity

Radiative opacity of plasmas is an important parameter, which couples into the equation of radiative transportation and affect strikingly the radiative transportation process of hot plasmas, as well as a crucial factor for the design of nuclear weapons. With the development of the theory of atomic structure and computer technology, in addition to the progress of experiment, the calculation of opacity is approaching higher accuracy and reliability. Now there are mostly four theoretical models established for the calculation of opacity: AA(average atom), STA(super transition arrays), UTA (unresolved transition array) and DTA (detailed term accounting). The DTA model has the highest accuracy and the most expensive computational cost in the above four models, which can be used for the calculation of the lighter elements but encounter difficulties in the calculation of heavy elements. Compared with other models, the AA model has the smallest computation cost but a coarser result. As for hot dense plasma of heavy elements, the calculation using AA model can not only guarantee acceptable precision but also reduce the computation cost compared with the DTA model. In this thesis, the opacity of heavy elements Al, Au and Pu in hot dense conditions are calculated using SCF (self-consistent field) method based on the AA model in the framework of central-field single-electron approximation, emphasized on the relativistic-effect of electrons in inner shells and the contribution of electric quadrupole radiation (E2). The results showed that the contribution of quadrupole radiation to the opacity of heavy elements in hot dense conditions is remarkable.